The Pawnee Fire that broke out Saturday near the community of Clearlake Oaks has destroyed 12 buildings and threatened an additional 600 as it burned out of control across about 12 square miles (31 sq. kilometers). Authorities ordered people to evacuate all homes in the Spring Valley area, where about 3,000 people live.

“What we’re stressing is that people, when they get the evacuation order, they heed it immediately and get out and stay out until it is safe to return,” state Department of Forestry and Fire Protection Battalion Chief Jonathan Cox said. “This is one of four large fires burning in Northern California. It’s a good reminder that fire season is upon us.”

Erratic wind and heat gripping a swath of California from San Jose to the Oregon border drove the flames, which were north of the wine country region where…